4 Answers
4

You can load jpegs into Adobe Camera Raw from bridge and have all the same options as processing a raw file. So you can choose the correct colour temperature and then convert several files with the same settings.

The level adjustment feature in Photoshop has the droppers for picking the white, black, and neutral points from the image. That would be quick approach, though you'd probably have to play with it a little from some images.

I do this quite often in Paint Shop Pro, using the Manual Color Correction feature. By consecutively right-clicking and left-clicking on the same patch of the picture that should be white or gray, you end up with "before" and "after" colors that are identical. Then you modify the "after" so that it has less saturation, taking it closer to pure white or gray. If you don't have anything in the picture in the white to gray range to sample from, you can sample from other colors and make them match one of the built-in samples or any other arbitrary color.

That's handy to know, as the friend in question has Paint Shop Pro, so I can train them to do it themselves :)
–
Rowland Shaw♦Sep 17 '10 at 10:56

@Rowland, I should also mention that there are other methods in Paint Shop Pro that might be simpler, but I prefer this method as it gives the most flexibility. The Manual Color Correction feature is hidden in later versions, you need to customize the menu or toolbar to bring it back.
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Mark RansomSep 18 '10 at 2:07

If you don't have Photoshop (some of us prefer to use the camera to create the art rather than the computer) then there are other options. I use Nikon's NX2 software for all post processing, it's very quick, clean and easy. You can download a trial that has no limitation other than a 60 day limit from Nikon's web site ... http://nikonimglib.com/cnx2/

To correct the white balance you need to find something on each image that is meant to be a shade of white and then use the Neutral Control Point and click on it. I have found this corrects over 90% of any white balance issues with a single click!

Since the question is tagged photoshop, why would you assume they didn't have it and want to use it?
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Peter BoughtonSep 17 '10 at 9:35

@Peter Boughton - the OP may be using PS, but I don't see why not to add an answer that solves the problem w/o the use of it, and on the way to help many other (PS-less) photographers.
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ysapOct 4 '11 at 1:07